'Late Night With Conan O'Brien'

Dan Edelson / NBC Universal

The date: Feb. 21, 2009 The guest: Former "SNL-er" Will Ferrell came on as George W. Bush, but soon tore off his suit to reveal a green leprechaun outfit well-known to fans of the show. Then former sidekick Andy Richter returned to watch clips from old shows, and the White Stripes performed a slow version of "We're Going to Be Friends."

The date: Feb. 21, 2009 The guest: Former "SNL-er" Will Ferrell came on as George W. Bush, but soon tore off his suit to reveal a green leprechaun outfit well-known to fans of the show. Then former sidekick Andy Richter returned to watch clips from old shows, and the White Stripes performed a slow version of "We're Going to Be Friends." (Dan Edelson / NBC Universal)

The date: Feb. 21, 2009 The guest: Former "SNL-er" Will Ferrell came on as George W. Bush, but soon tore off his suit to reveal a green leprechaun outfit well-known to fans of the show. Then former sidekick Andy Richter returned to watch clips from old shows, and the White Stripes performed a slow version of "We're Going to Be Friends."